add support for hot reloading

src/login/static_provider.rs

@@ -1,6 +1,8 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 use std::path::PathBuf;
+use tokio::sync::watch;
+use tokio::signal::unix::{signal, SignalKind};
 
 use anyhow::{anyhow, bail, Result};
 use async_trait::async_trait;
@@ -9,48 +11,59 @@ use crate::config::*;
 use crate::login::*;
 use crate::storage;
 
-pub struct StaticLoginProvider {
-    user_list: PathBuf,
+#[derive(Default)]
+pub struct UserDatabase {
     users: HashMap<String, Arc<UserEntry>>,
     users_by_email: HashMap<String, Arc<UserEntry>>,
 }
 
-impl StaticLoginProvider {
-    pub fn new(config: LoginStaticConfig) -> Result<Self> {
-        let mut lp = Self {
-            user_list: config.user_list.clone(),
-            users: HashMap::new(),
-            users_by_email: HashMap::new(),
-        };
-
-        lp
-            .update_user_list()
-            .context(
-                format!(
-                    "failed to read {:?}, make sure it exists and it's correctly formatted", 
-                    config.user_list))?;
-
-        Ok(lp)
+pub struct StaticLoginProvider {
+    user_db: watch::Receiver<UserDatabase>,
 }
 
-    pub fn update_user_list(&mut self) -> Result<()> {
-        let ulist: UserList = read_config(self.user_list.clone())?;
+pub async fn update_user_list(config: PathBuf, up: watch::Sender<UserDatabase>) -> Result<()> {
+    let mut stream = signal(SignalKind::user_defined1()).expect("failed to install SIGUSR1 signal hander for reload");
 
-        self.users = ulist
+    loop {
+        let ulist: UserList = match read_config(config.clone()) {
+            Ok(x) => x,
+            Err(e) => {
+                tracing::warn!(path=%config.as_path().to_string_lossy(), error=%e, "Unable to load config");
+                continue;
+            }
+        };
+
+        let users = ulist
             .into_iter()
             .map(|(k, v)| (k, Arc::new(v)))
             .collect::<HashMap<_, _>>();
 
-        self.users_by_email.clear();
-        for (_, u) in self.users.iter() {
+        let mut users_by_email = HashMap::new();
+        for (_, u) in users.iter() {
             for m in u.email_addresses.iter() {
-                if self.users_by_email.contains_key(m) {
-                    bail!("Several users have same email address: {}", m);
+                if users_by_email.contains_key(m) {
+                    tracing::warn!("Several users have the same email address: {}", m);
+                    continue
                 }
-                self.users_by_email.insert(m.clone(), u.clone());
+                users_by_email.insert(m.clone(), u.clone());
             }
         }
-        Ok(())
+
+        tracing::info!("{} users loaded", users.len());
+        up.send(UserDatabase { users, users_by_email }).context("update user db config")?;
+        stream.recv().await;
+        tracing::info!("Received SIGUSR1, reloading");
+    }
+}
+
+impl StaticLoginProvider {
+    pub async fn new(config: LoginStaticConfig) -> Result<Self> {
+        let (tx, mut rx) = watch::channel(UserDatabase::default());
+
+        tokio::spawn(update_user_list(config.user_list, tx));
+        rx.changed().await?;
+
+        Ok(Self { user_db: rx })
     }
 }
 
@@ -58,7 +71,8 @@ impl StaticLoginProvider {
 impl LoginProvider for StaticLoginProvider {
     async fn login(&self, username: &str, password: &str) -> Result<Credentials> {
         tracing::debug!(user=%username, "login");
-        let user = match self.users.get(username) {
+        let user_db = self.user_db.borrow();
+        let user = match user_db.users.get(username) {
             None => bail!("User {} does not exist", username),
             Some(u) => u,
         };
@@ -89,7 +103,8 @@ impl LoginProvider for StaticLoginProvider {
     }
 
     async fn public_login(&self, email: &str) -> Result<PublicCredentials> {
-        let user = match self.users_by_email.get(email) {
+        let user_db = self.user_db.borrow();
+        let user = match user_db.users_by_email.get(email) {
             None => bail!("No user for email address {}", email),
             Some(u) => u,
         };

src/main.rs

@@ -42,7 +42,7 @@ enum Command {
     Provider(ProviderCommand),
 
     #[clap(subcommand)]
-    /// Specific tooling, should not be part of a normal workflow, for debug & experimenting only
+    /// Specific tooling, should not be part of a normal workflow, for debug & experimentation only
     Tools(ToolsCommand),
     //Test,
 }

src/server.rs

@@ -18,21 +18,21 @@ pub struct Server {
 
 impl Server {
     pub async fn from_companion_config(config: CompanionConfig) -> Result<Self> {
-        let login = Arc::new(StaticLoginProvider::new(config.users)?);
+        let login = Arc::new(StaticLoginProvider::new(config.users).await?);
 
         let lmtp_server = None;
-        let imap_server = Some(imap::new(config.imap, login).await?);
+        let imap_server = Some(imap::new(config.imap, login.clone()).await?);
         Ok(Self { lmtp_server, imap_server })
     }
 
     pub async fn from_provider_config(config: ProviderConfig) -> Result<Self> {
         let login: ArcLoginProvider = match config.users {
-            UserManagement::Static(x) => Arc::new(StaticLoginProvider::new(x)?),
+            UserManagement::Static(x) => Arc::new(StaticLoginProvider::new(x).await?),
             UserManagement::Ldap(x) => Arc::new(LdapLoginProvider::new(x)?),
         };
 
         let lmtp_server = Some(LmtpServer::new(config.lmtp, login.clone()));
-        let imap_server = Some(imap::new(config.imap, login).await?);
+        let imap_server = Some(imap::new(config.imap, login.clone()).await?);
 
         Ok(Self { lmtp_server, imap_server })
     }